An Inexpensive & Compact Allsky Camera?

A decent DIY Allsky Camera can easily cost over $400 USD to build. A “low-cost” Raspberry Pi 4B based system with HQ camera and wide-angle lens with enclosure will cost over $250 USD to build. If that price range is too steep for you, you might consider a very low cost option. It will not be an ALL sky camera but will provide a fun experience with quality images and videos. Consider building an inexpensive sky camera that covers about 1/4 of the sky. This will still provide good coverage and captures very impressive day and night sky images and time-lapse videos using the Allsky software found on github: There is an updated version of this software, currently in test (February 2023), that supports the Pi Camera Module 3. I expect that it will escape soon 🙂

You can build a compact component-based sky camera for less than $75 USD or about $100 USD with a very nice enclosure.

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Raspberry Pi 4 Based AllSky Cameras

Version 1 – PVC pipe & fittings

A couple of months back, I put together an all sky camera system for the Martz-Kohl Observatory near Jamestown, in Western New York. An all sky camera provides a (near) 180-degree fisheye view of the sky. This project was a joint effort with other members of the observatory. One member supplied parts for the system enclosure while another donated a Raspberry Pi 4B single board computer and ZWO ASI224MC astro-camera and lens. Others donated time and expertise for assembling and mounting the system on top of the observatory. There were definite lesons learned as the original assembly leaked under severe weather. The fight with dew and frost is ongoing. It will take some effort and thought to automate a method of keeping the dome clear. For now, an occasional cleaning of the dome’s’s exterior keeps everything working 🙂

Version 2 – sealed enclosure

SO, with lessons learned, I built a version 2 all sky camera system! As opposed to the PVC pipe enclosure, I went with a waterproof box, similar to what other DIY folks have used. I used parts that I had lying around: a Raspberry Pi 4B, R-Pi HQ camera, an Argon Fan HAT and a USB 3 SSD that I was no longer using. I purchased a lens, dome, USB C cable mount, and various hardware and sealants.

On both systems, I use the Allsky software which is open source and available on github.

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MongoDB 5.0 under Raspberry Pi OS (64-bit)

MongoDB 5.0.5 for Raspbian Pi OS (64-bit)

[UPDATED: 12 Jan 2022 with MongoDB 5.0.5 binaries] There is no official support from MongoDB for Debian ARM 64 or Raspbian64 Linux OS (now known as Raspberry Pi OS 64-bit).  You can, however, compile the MongoDB Community Edition from source.  I did just that 🙂  It did, however, take three days and a burnt Raspberry Pi 4 to accomplish 🙁  I’ll provide a link to instructions to create the executables for mongod, mongos and mongo — as well as provide a few tips to successfully compile.  Better and easier than that, I provide links to already compiled versions with instructions on how to install and use.

I recently decided to “check-in” on the status of Raspbian64, the 64 bit version of Raspberry Pi OS which is not yet released. I had been using Ubuntu Server 20.04 ARM 64-bit on a couple of Raspberry Pi 4s for various projects. One benefit of Ubuntu was official support for MongoDB. I was looking for a complete optimized Raspbian OS with GUI AND MongoDB. Searching around, I did not find what I wanted. I decided to try and create it.

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MongoDB 4.4 & Ubuntu 20.04 on Raspberry Pi 4

Latest MongoDB on Raspberry Pi 4

Have a Raspberry Pi 4 with 4GB or 8GB of RAM and want to run the popular noSQL database, MongoDB? Read on for installing and running the latest 64-bit versions of MongoDB and Ubuntu 20.04.

The short (TL;DR) instructions are to read and follow the official install guides for 64-bit Ubuntu Server 20.04 and MongoDB 4.4 for ARM 64. The longer detailed instructions follow…

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MathTerms iOS App is now available

What is MathTerms? Here is the description from the Apple App Store.

MathTerms is an illustrated glossary of mathematics terms in English and Spanish. The free iOS app includes almost 500 entries for middle- and high-school mathematical concepts. To help learners master speaking as well as reading, it encompasses audio pronunciations of terms, by English and Spanish native speakers. A flash-card quiz game is included, enabling students to study selected terms in an interactive environment.

A few years back, I created a mobile app that was a glossary of mathematics terms for middle- and high-school students and teachers. It was written in a now defunct Javascript-based framework. As iOS evolved, my app no longer functioned – and I dropped it from the Apple App Store.

Apple recently introduced its SwiftUI framework that is a tool to build user interfaces with a declarative Swift syntax. You can simply drag and drop widgets and then add logic via the Swift programming language. I decided to revisit my old MathTerms app as a good way to learn about this new framework and make MathTerms available again.

You can learn more about the app using the MathTerm menus at the top of this page.


HDMI Video Capture via USB Adapter

R-Pi Video displayed on a Mac Mini

View your Raspberry Pi (Zero, 2, 3, 4) display on-the-go without VNC or prior configuration. Great inexpensive device for your toolbox! Laptop required 🙂

I have a bunch of R-Pis of various flavors. I also use R-Pi cameras (regular, IR and HQ) on a regular basis. I don’t always know the WiFi or network config for where I’m going. Sure, you can change files on your SD Card to configure things for WiFi or connect to a laptop via VNC (if you know about access point configs or know the network ahead of time). A GREAT tool I’ve added to my toolbox is an inexpensive video encoder – also known as an HDMI Video Capture USB Device. I picked up 2, at different times, off eBay for about $15/each. They are very small and light – about 2″ x 1″.

Video Capture Adapter

I was prompted to write this as I saw an Adafruit Tweet that mentioned their (new) product, “USB 2.0 to HDMI Video Capture Adapter.” A good deal at $20 with HDMI cable. All you do is plug your video-out from an R-Pi into the HDMI input and plug-in the adapter to a USB port. It then acts like a webcam in that you can use apps to view the R-Pi display on Mac, PC or Linux laptop (or desktop). This is an awesome, easy way to view video to focus a camera or preview an image or video stream – without stutter or dropped frames – that you get using VNC.

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Timelapse video from a remote source

Infrared Sky Camera

This is yet another take on how-to create a time-lapse video.  In my case, a website updates a photo of the sky on a regular basis. I wanted to turn that into a time-lapse video and deploy to another, or possibly the same, website. I decided to use a Raspberry Pi 4 that was “sitting around.”

My project evolved as I tried different techniques and apps. I ended up creating a couple of bash scripts to do the job. I used the “ffmpeg” audio/video framework as it was bash command line friendly. I have tested my scripts on my Raspberry Pi 4 with Raspbian OS as well as on different Linux boxes running Ubuntu and Debian.

For how-to scripts with instructions, click on “more

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MongoDB 4.2.x (64-bit) on Raspberry Pi 4

Ubuntu 18.04.x (ARM 64-bit) is now available for the Raspberry Pi 4. While not an officially supported OS from either the Foundation or Ubuntu, James A. Chambers has been working on a port for the Raspberry Pi 4. A 64-bit OS is required to run 64-bit MongoDB 4.2.x. MongoDB (the company) just recently provided a 64-bit ARM version for Ubuntu 18.04. I will show how to install this version of MongoDB under Ubuntu 18.04 on the Raspberry Pi 4.

Note that my Raspberry Pi 4 has 4GB RAM. I believe from past experience that 2GB is sufficient to run MongoDB. I have had issues with a 1GB RAM system but worked around by creating a swap disk.

Please read my instructions carefully and copy and paste where you can. I have noticed a couple of typos on the MongoDB website where the “ARM” keyword was missing in some commands.

First, follow the instructions on James A Chambers website to install Ubuntu 18.04. I used “Release v17” but there may now be a newer release. Make sure you have updated the bootloader per James’ Raspberry Pi 4 Bootloader Guide. In short do a “rpi-update” and a “rpi-eeprom-update” under Raspbian BEFORE burning and booting-from the Ubuntu 18.04 image. I booted with ethernet connected to establish keys, etc. with Ubuntu. I chose not to use a GUI but again, James mentions several available in his write-up.

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PyPortal Blackjack game: uses sprites, touch, audio

PyPortal Blackjack Game

I recently visited relatives that frequent casinos at Niagara Falls. I decided to brush-up my Blackjack skills (or lack thereof). I was also looking to enhance my Python (CircuitPython, that is) skills by developing projects, such as this Blackjack game 😉

The Adafruit PyPortal IoT Device with display has everything you need to connect to the internet, build rich GUIs, connect various sensors AND is easy to program in CircuitPython using Adafruit libraries. The “Explore & Learn” area on the Adafruit website is filled with great sample code, nifty apps and lots of inspiration.

When not working on a personal project, I install various projects from Adafruit on my PyPortal.  A few of my favorites are the PyPortal Weather Station, the PyPortal ISS Tracker, and the PyPortal NASA Image of the Day Viewer.  I also examine and learn techniques from other projects such as the PyPortal Alarm Clock.

After examining the code for these projects and reading documentation for the PyPortal and CircuitPython Libraries, I started developing my Blackjack game. Code examples were great but I had a harder time finding the libraries I needed in order to understand how graphics were displayed. A short guide, “CircuitPython Display Support Using displayio” really helped me understand the use of sprites, graphics as bitmaps, groups, etc. Definitely worth checking out.

Card Element Sprites in a TileGrid
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PyPortal – access the micro-SD Card

PyPortal IoT Device

The Adafruit PyPortal is a great little IoT device with lots of projects available. It’s an awesome H/W and S/W platform that inspires many creative ideas. The PyPortal uses an ATMEL (Microchip) ATSAMD51J20, and an Espressif ESP32 Wi-Fi coprocessor. PyPortal has a 3.2″ 320 x 240 color TFT resistive touch screen and has several built-in sensors. It also has support for a micro-SD Card. The device itself shows up as a USB drive when plugged into a computer — but not the micro-SD Card 🙁

Software support for PyPortal is via CircuitPython. There is a great Integrated Development Environment (IDE) available in the form of Mu. Mu is a simple Python editor that also has a built-in serial-port terminal. It allows command-line input of CircuitPython for instant programming, testing, and debugging. This feature is referred to as the REPL (Read-Evaluate-Print-Loop). Deployment of code to a PyPortal is immediate with Mu’s “Save” function.

As I was experimenting with my PyPortal, I wanted to put code and resources (images, fonts, code) on a removable micro-SD Card. Easy to do on my computer but not obvious how to do on PyPortal 🙁 I looked at several PyPortal sample apps and perused CircuitPython docs available on the Explore and Learn Area on the Adafruit websitet

I’m sharing what I learned in a hopefully concise manner to save others time and frustration 😉

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